SOD1 and amyotrophic lateral sclerosis: Encoding a Cu/Zn dismutase enzyme that provides defense against toxic superoxide free radicals, SOD1 was the first gene linked to ALS (Rosen et al., 1993), and its mutation is responsible for ≈12% and ≈1% of fALS and sALS patients, respectively (Renton et al., 2014).